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Sep 19, 2018

Assessing Corn Yield Potential

Estimating corn yield potential can help with harvest decision making.

Estimating corn yield potential can help with harvest decision making. The corn yield component method can be used as early as the R3 (milk) growth stage. The ear weight method is used after corn is physiologically mature.

Crop uniformity has a large influence on the accuracy of any estimation method. Samples should be taken randomly throughout a field to provide the best yield estimate. One sample for every 10 to 15 acres should be sufficient unless conditions are variable. More samples should be taken to represent a non-uniform field and improve the accuracy of the estimate. The yield component method and the ear weight method are two ways to estimate corn grain yield potential prior to harvest. Each method may produce yield estimates that are within 20 bu/acre of actual yield.2

Corn-Yield Component Method

This method is used widely and can be used as early as the milk growth stage (R3). It’s risky to make estimates prior to R3 because stresses can affect kernel development and cause kernel abortion.3 This method is based on the assumption that grain yield can be estimated using the number of ears per acre, number of kernel rows per ear, number of kernels per row, and kernel weight. The first three components can be measured from field samples, but kernel weight is unknown until physiological maturity (black layer) and must be represented by a calculated factor. The average value for kernel weight (90) is derived using 85,000 kernels per 56 pound bushel (Table 2, Page 2)1. Some agronomists think that a kernel weight of 80 to 85 is a more appropriate factor for current use because kernel size has increased since this formula was first developed many years ago.3

Step 1. At each sample site, measure 1/1000th of an acre (Table 1). Don’t sample nubbins, abnormal ears, aborted kernels or count dropped ears or ears on severely lodged plants. Count kernels where there are complete rings of kernels around the cob and avoid counting kernels on the extreme ends of the ear (Figure 1).1

Step 2. Count the number of kernel rows per ear on every fifth ear and determine the average.

Step 3. On the same fifth ears, count the number kernels per row and determine the average.

Step 4. To determine an estimate of yield potential per acre at each sample site, multiply the number of ears times the average number of rows times the average number of kernels and divide by 90 or the factor that best represents growing conditions (Table 2).

Step 5. Repeat this procedure at a representative number of sample sites in the field. Calculate the average yield potential for all of the sites to get an estimate of the yield potential of the entire field.

Example: Harvestable ear count is 30. The average number of kernels per ear from every fifth ear is 511. Growing conditions were average (85). The estimated yield potential for that site would be (30 times 511) divided by 85, or a 180 bu/acre estimate of yield potential.3

Poor conditions during grain fill can cause lower kernel weights, resulting in an underestimation of yield potential with the yield component method. Conversely, it can overestimate yield potential if kernel weight is higher than normal, during superior growing conditions.3 Kernel size and weight can vary by corn product and environmental conditions, which can compromise the accuracy of the estimate.

Corn-Ear Weight Method

This method should only be used after corn has reached physiological maturity or black layer (R6). This method may be more accurate than the yield component method because it is based on actual kernel weight. It does have a factor to account for average shell out percentage.3 Sample several representative sites in a field. Count the number of harvestable ears in 1/1000th of an acre at each site (Table 1) at several random sites throughout the field. At each site: 1) weigh every fifth ear and calculate the average ear weight per site, 2) hand shell kernels from those ears, and 3) determine the average grain moisture with a moisture tester.

Calculation Steps for each site:

Step 1. Multiply the number of ears by the average ear weight.

Step 2. Multiply average grain moisture by the factor 1.411.

Step 3. Add 46.2 to the average grain moisture ×1.411 (step 2).

Step 4. Divide result from step 1 by the result from step 3.

Step 5. Multiply result from step 4 by 1,000.

Example: The number of harvestable ears is 24. Average ear weight of every fifth ear is 0.5 pound. The average grain moisture is 30%. The estimated yield potential is [(24 x 0.5) divided by ((1.411 x 30) + 46.2)] times 1,000, or 135 bu/acre.2 There are several other methods to estimate corn yield potential that are less widely used than the yield component and ear weight methods.2

XtendiMax® herbicide with VaporGrip® Technology is part of the Roundup Ready® Xtend Crop System and is a restricted use pesticide. ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. It is a violation of federal and state law to use any pesticide product other than in accordance with its labeling. XtendiMax® herbicide with VaporGrip® Technology and products with XtendFlex® Technology may not be approved in all states and may be subject to use restrictions in some states. Check with your local product dealer or representative or U.S. EPA and your state pesticide regulatory agency for the product registration status and additional restrictions in your state. For approved tank-mix products and nozzles visit XtendiMaxApplicationRequirements.com.

Commercialization is dependent on multiple factors, including successful conclusion of the regulatory process. The information presented herein is provided for educational purposes only, and is not and shall not be construed as an offer to sell, or a recommendation to use, any unregistered pesticide for any purpose whatsoever. It is a violation of federal law to promote or offer to sell an unregistered pesticide.

Do not export Roundup Ready® Alfalfa seed or crop, including hay or hay products, to China pending import approval. In addition, due to the unique cropping practices do not plant Roundup Ready® Alfalfa in Imperial County, California, pending import approvals and until Forage Genetics International, LLC (FGI) grants express permission for such planting.

Forage Genetics International, LLC (“FGI”) is a member of Excellence Through Stewardship® (ETS). FGI products are commercialized in accordance with ETS Product Launch Stewardship Guidance, and in compliance with FGI’s Policy for Commercialization of Biotechnology-Derived Plant Products in Commodity Crops. Certain products have been approved for import into key export markets with functioning regulatory systems. Any crop or material produced from this product can only be exported to, or used, processed or sold in countries where all necessary regulatory approvals have been granted. It is a violation of national and international law to move material containing biotech traits across boundaries into nations where import is not permitted. Growers should talk to their grain handler or product purchaser to confirm their buying position for this product. Growers should refer to http://www.biotradestatus.com/ for any updated information on import country approvals. Excellence Through Stewardship® is a registered trademark of Biotechnology Industry Organization.

Monsanto Company is a member of Excellence Through Stewardship® (ETS). Monsanto products are commercialized in accordance with ETS Product Launch Stewardship Guidance, and in compliance with Monsanto’s Policy for Commercialization of Biotechnology-Derived Plant Products in Commodity Crops. This product has been approved for import into key export markets with functioning regulatory systems. Any crop or material produced from this product can only be exported to, or used, processed or sold in countries where all necessary regulatory approvals have been granted. It is a violation of national and international law to move material containing biotech traits across boundaries into nations where import is not permitted. Growers should talk to their grain handler or product purchaser to confirm their buying position for this product. Excellence Through Stewardship® is a registered trademark of Excellence Through Stewardship.

ALWAYS READ AND FOLLOW DIRECTIONS FOR USE ON PESTICIDE LABELING. IT IS A VIOLATION OF FEDERAL AND STATE LAW to use any pesticide product other than in accordance with its labeling. NOT ALL formulations of dicamba or glyphosate are approved for in-crop use with Roundup Ready 2 Xtend® soybeans. ONLY USE FORMULATIONS THAT ARE SPECIFICALLY LABELED FOR SUCH USES AND APPROVED FOR SUCH USE IN THE STATE OF APPLICATION. Contact the U.S. EPA and your state pesticide regulatory agency with any questions about the approval status of dicamba herbicide products for in-crop use with Roundup Ready 2 Xtend® soybeans.

Roundup Ready 2 Xtend® soybeans contains genes that confer tolerance to glyphosate and dicamba. Glyphosate will kill crops that are not tolerant to glyphosate. Dicamba will kill crops that are not tolerant to dicamba. Glufosinate will kill crops that are not tolerant to glufosinate. Contact your Monsanto dealer or refer to Monsanto’s Technology Use Guide for recommended weed control programs.

B.t. products may not yet be registered in all states. Check with your Monsanto representative for the registration status in your state.

IMPORTANT IRM INFORMATION: RIB Complete® corn blend products do not require the planting of a structured refuge except in the Cotton-Growing Area where corn earworm is a significant pest. SmartStax® RIB Complete® corn blend is not allowed to be sold for planting in the Cotton-Growing Area. See the IRM/Grower Guide for additional information. Always read and follow IRM requirements.

Performance may vary, from location to location and from year to year, as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible and should consider the impacts of these conditions on the grower’s fields.

The Climate FieldView™ services provide estimates or recommendations based on models. These do not guarantee results. Consult your agronomist, commodities broker and other service professionals before making financial, risk management, and farming decisions. Information and recommendations we provide do not modify your rights under insurance policies purchased through our affiliates. More information at www.climate.com/disclaimers.